SEDL / STP / STP1387-EB / STP13503S

Experiences with Lifetime Prediction Under Multiaxial Random Loading

Pötter, K
Institute for Plant Engineering and Fatigue Analysis (IMAB), Technical University of Clausthal, Clausthal-Zellerfeld,

Yousefi, F
Institute for Plant Engineering and Fatigue Analysis (IMAB), Technical University of Clausthal, Clausthal-Zellerfeld,

Zenner, H
Institute for Plant Engineering and Fatigue Analysis (IMAB), Technical University of Clausthal, Clausthal-Zellerfeld,

Pages: 16    Published: Jan 2000

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Abstract

A number of multiaxial fatigue criteria have been developed during the past decades. They can be subdivided into hypotheses of the critical plane approach, hypothesis of integral approach, as well as empirical criteria. In the case of the integral approach the equivalent stress is calculated as an integral of the stresses over all intersection planes, whereas in the case of the critical plane approach only the intersection plane with the critical stress combination is considered. The difference between the two approaches is insignificant with proportional in-phase loading, but becomes clearly visible in the case of noncorrelated or phase-shifted loading. In the present paper the two approaches are compared. For the model verification, variable-amplitude tests under combined bending and torsion with smooth and notched specimens are applied. The integral approach was found to be superior to the critical plane approach under varying principal stress directions.